Clutching and declutching means for feeding mechanism of down-feed grinders and the like



Dec. 22, 1959 J, p E ow cz ETAL 2,917,875

CLUTCHING AND DECLUTCHING MEANS FOR FEEDING MECHANISM OF DOWN-FEED GRINDERS AND THE LIKE Filed April 13, 1956 2 Sheets-Sheet 1 nvvavrons.

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Dec. 22, 1959 J, PIETROWICZ ETAL 2,917,875

CLUTCHING AND DECLUTCHING MEANS FOR FEEDING MECHANISM OF DOWN-FEED GRINDERS AND THE LIKE Filed April 15, 1956 2 Sheets-Sheet 2 1111M l iiilHin; lilii.i; lNVENTO/PS 42 Edwin c1. flz'efz'ozzlzcz /7 .459 52 r! dill/[M21225 United States Patent CLUTCHING AND DECLUTCHING MEANS FOR FEEDING MECHANISM OF DOWN-FEED GRIND- ERS AND THE LIKE Edwin J. Pietrowicz and Earl C. Williams, Syracuse,

N.Y., assignors to General Motors (Iorporation, Detroit, Mich., a corporation of Delaware Application April 13, 1956, Serial No. 578,030 Claims. c1. 51-165) This invention is primarily concerned with clutching devices generally and control means including clutching means particularly related to machines such as downfeed grinders, etc.

One important objective of the invention is to provide a control adapted for machines such as downfeed grinders which is capable of feeding automatically and cutting out at a predetermined point with extreme precision, for example, within one-ten-.thousandth (.0001) of an inch if necessary. So far as is known, no control means has as yet been provided for machines such as downfeed grinders which even remotely approaches the accuracy obtainable with the invention embodied in the proposed device. The invention is illustrated and described in connection with a downfeed grinder having a reciprocating worktable upon which a work piece is disposed and comprises a clutch spring engaging driving and driven clutch drum members. One of the drum members is oscillated by means of a rocker arm which is disposed in the path of an actuating dog mounted on the reciprocating machine table. When the spring clutch engages the two clutch drums each pass of the table rotates the rocker arm and a pinion connected to the driven drum which, in turn, meshes with a ring gear operatively connected to the downfeed mechanism. A springeloaded solenoid is provided and includes aclutch disengaging rod which when the solenoid is de-energized bears against the end of the clutch spring 'so as to un-' wind the spring thereby breaking or preventing the clutch action between the driving and driven clutch members. The downfeed may be interrupted automatically at any time at a predetermined point in the operation by providing a limit switch in the path of a projection on the ring gear. By prepositioning the ring gear, the projection may be adjusted to any desired position relative to the limit switch. As the projection contacts the limit switch the circuit to the solenoid is broken and the downfeed action stops.

It is, therefore, a broad object of the present invention to combine a one-way clutch mechanism, which includes a reciprocating driving drum and a driven drum spanned by a coil spring clutch tending to wind up on the drums when the driving member turns in one direction and unwind when it is driven in the opposite direction, with further means to unwind the spring regardless of the direction of rotation of the driving member.

It is a further object of this invention to provide a feed control fora downfeed grinder which can be regulated with extreme precision to automatically discontinue the downfeed grinding operation when a desired depth of cut has been achieved.

For a fuller understanding of the inventionv and the above and other objects thereof attention is directed to the accompanying detailed description and drawings, in

which:

Fig. l is a perspective, fragmentary view of such a machine showing a portion of the worktable and a ring gear mounted on the feed attachment of the machine with .7 2,917,875 Patented Dec. 22, 1959 the novel control and clutch means interposed therebetween.

Fig. 2 is an enlarged view of the control portion of Fig. l with parts cut away and in section to show various details of the assembly.

Fig. 3 is a view in plan with portions removed and in section further illustrating the details of the novel clutching mechanism and is taken on line 3-3 of Fig. 4.

Fig. 4 is a side view in elevation taken on the line 44 of Fig. 3 and serves to illustrate how the solenoid-com trolled rod acts on the clutch spring to prevent clutching action between the driving and driven clutch drums.

Referring now to the drawings, a portion of a grinding machine commonly known as a downfeed grinder is indicated generally by a numeral 2. The downfeed grinder includes a reciprocating worktable 4 having fixed thereto by set screw 6 an actuating dog 8. The worktable 4 reciprocates so as to periodically engage and press a rocker arm 10 which forms a part of the novel control mechanism to be described in more detail shortly. Also forming a part of the machine, and fragmentarily shown, is the feed attachment of the grinding machine indicated by a numeral 12 and including ring gear 14. The ring gear 14 is actually mounted in the present instance on the. one-ten-thousandth (.0001) feed attachment of the grinding machine.

The control mechanism in part includes a housing 16 having an end Wall 18 in which is journalled one end of a shaft 20. The housing 16 is mounted on the support 17 forming a part of the grinding machine frame. Keyed by a key 22 to shaft 20 adjacent the end bearing in the wall 18 is a pinion 24 which meshes with the ring gear 14. Slipped over a necked-down end 26 of pinion 24 is an internal bearing 28 which is pressed into the housing 16. The journal bearing 28 is further held in place in housing 16 by a set screw 30 engaging in the groove 32 of bearing 28 (see Fig. '1). Also keyed by key 35 to shaft 20 is the driven dnlm 34 of the clutch assembly of the control. The driving drum 36 of the clutch assembly is secured by studs 38'to the rocker arm 10 so as to turn therewith. Spanning the driving and driven drums 36 and 34, which have cylindrical outer friction surfaces40 and 42, respectively, is a coil spring clutch 44 whose internal diameter is slightly lessthan the outer diametersof surfaces 40 and 42 so that it is a close friction slip fit over the surfaces of the two clutch drums. The opposite ends 46 and 48, respectively, ofthe spring 44 are bent to extend axially so that end 46 resides flush in a groove 50 in driving drum 36 and end 48 extends transversely into a groove 52 provided in one end of Y the internal bearing 28. The end 48 is adjacent the end of a rod or bar 54 operatively connected to and actuable by a solenoid assembly56. A suitable spring 58 extends between a shoulder 60 on rocker arm 10 and support 17 so as to return rocker arm 10 after it has been momentarily depressed by the actuating dog 8.

- that the worktable makes a pass so that the actuating dog The operation of the assembly is as follows: Assuming 8 passes over the rocker arm 10 thereby depressing it, then drum 36 will be limitedly oscillated or rotated in a clockwise direction, as viewed in Fig. 2. Such motion is limited to oscillations of less than 45 rotation because of engagement of shoulder 60 with support 17.

wind. Because the ring gear, the pinion and shaft 20 offer a certain amount of resistance to turning in either direction, drum 34 will not turn. In other words, from the foregoing description of operation it will be appreciated that the clutch is a one-way clutch which due to the rocking or oscillating action of rocker arm of less than 45 rotation causes intermittent rotation in one direction only of pinion 24 and ring gear 14.

Assuming now that it is desired to cut off the grinding operation after the feeding mechanism has fed down the work to the depth of cut desired, the solenoid 56 may be energized or, as in the present application, de-energized to cause the rod 54 to exert pressure against the end 48 so as to unwind coil spring clutch 44. The rod 54 moves a sufficient distance in the groove 52 to increase the internal diameter of spring 44 so that regardless of the direction of rotation or oscillation of drum 36 there will be no clutching action between spring 44 and friction surfaces 40 and 42 of the driving and driven drums 36 and 34.

As previously mentioned in the general description of the machine, the declutching feature of the device may be automatically controlled when the desired depth of cut has been reached by placing a projection 61 on the ring gear which is mounted on the one-ten-thousandth (.0001) feed attachment of the grinding machine. This projection 61 may be prepositioned before the grinding operation is begun so as to actuate a switch 62 when the desired depth of cut has been reached which switch 62 when placed in circuit with a solenoid 56 will actuate the solenoid so as to cause rod 54 to unwind spring clutch 44 sufficiently to maintain drums 34 and 36 declutched regardless of whether rocker arm 10 is oscillating or not. It should be apparent from the foregoing description that declutching is practically instantaneous due to the close proximity of rod 54 to the end 48 of spring 44 and it is the maintenance of the relative positions of rod 54 and end 48 which enables the com trol to achieve such preciseness in the grinding operation.

The means for automatically cutting off the grinding operation would include aforementioned projection 61, the actuating switch 62 in circuit with a voltage source such as a battery 64, a stop-and-start switch 66 and the aforementioned solenoid 56. In addition, it will be appreciated that downfeed may be interrupted at any time merely by depressing the stop-and-start switch 66 to break the circuit including the solenoid 56. Since this solenoid is spring biased, breaking of the circuit causes rod 54 to unwind spring 44 enough to declutch the drums 34 and 36.

What we claim is:

l. A clutch device for the feeding mechanism of downfeed grinders and the like comprising, in combination,.

a support, a driving member mounted for rotation on said support and having a friction surface, means limiting said rotation to oscillation within a predetermined range, a driven member mounted for rotation on said support and having a friction surface, a coil spring clutch having turns about both of said surfaces and an end anchored to one of said members, and declutching means actuable to' unwind said coil spring clutch independent of the rotative position of said members within said range.

2. A one-way clutch device for the feeding mechanism of down-feed grinders and the like comprising a support, a driving drum mounted for oscillatory movements on said support and having a friction surface, a driven drum mounted for rotation on said support and having a friction surface, a coil spring clutch having turns about both'of said surfaces whereby said drums are clutched together during one half of an oscillation and declutched during the other half of the oscillation so as to provide intermittent rotation of the driven drum in one direction only, and declutching means operative to maintain said coil spring clutch sufficiently unwound to prevent clutching of said drums during both halves of the oscillations of said driving drum, comprising a longitudinally extending end on said coil spring clutch immediately outboard the periphery of one of said drums, and a solenoid tangentially positioned with respect to the one of said drums and engageable with said end upon energization thereof.

3. A one-way clutch device for the feeding mechanism of down-feed grinders and the like comprising a support, a driving member mounted for oscillatory movements of less than 45-degree rotation on'said support and having a friction surface, means limiting said member to such movements, a driven member mounted for rotation on said support and having a friction surface, a coil-spring clutch having turns about both of said surfaces and an end anchored to one of said members-whereby said members are clutched together during one half of an oscillation and declutched during the other half of the oscillation so as to provide intermittent rotation of the driven member in one direction only, and declutching means operative to maintain said coil spring clutch sufiiciently unwound to prevent clutching of said members during both halves of the oscillations of said driving member.

4. A one-way clutch device for the feeding mechanism of down-feed grinders and the like comprising a support, a driving member mounted for oscillatory movements of less than 45-degree rotation on said support and having a friction surface, means limiting said member to such movements, a driven member mounted for rotation on said support and having a-friction surface, a coil-spring clutch having turns about both of said surfaces and an end anchored to one of said members whereby said members are clutched together during one half of an oscillation and declutched during the other half of the oscillation so as to provide intermittent rotation of the driven member in one direction only, said coil-spring clutch having an abuttable end, and declutching means operative to maintain said coil-spring clutch sufiiciently unwound to prevent clutching of said members during both halves of the oscillations of said driving member comprising a solenoid-actuated rod adjacent the abuttable end of said coil-spring clutch adapted to engage said end uponactuation of said solenoid.

5. In combination with a down-feed grinding machine and the like including a feeding mechanism, control means therefor comprising a support, a driving member including a drum mounted for rotational oscillatory movements on said support, means limiting the movements of said driving member to less than one-eighth of a complete revolution, a driven member including a drum, said driven member being operatively connected to said feeding mechanism, a coil-spring clutch having turns about both of said drums, means responsive to working of said machine causing said movements of said driving member to thereby, provide intermittent feeding in one direction only, and declutching means responsive to a predetermined amount of feeding to maintain said coil spring clutch unwound sufficiently to prevent clutching of said members during all of said movements of said driving member and thereby discontinue any further feeding of said mechanism.

References Cited in the file of this patent UNITED STATES PATENTS 1,016,585 Solem Feb. 6, 1912 1,110,325 Hanson 'Sept. 15, 1914 1,767,472 Ostler June 24, 1930 1,928,162 Asbridge Sept. 26, 1933 2,660,899 McCammon Dec. 1, 1953 

